P0770, P0303, and P0420, 1999 TOYOTA - Camry XLE

Question

My Check engine light is on with all thre of these codes popping up;
P0303 - Cylinder 3 Misfire
P0420 - Catalyst System Efficiency Below Threshold Bank 1
P0770 - Shift Solenoid E

PLEASE, all im looking for is what do these codes mean?and what do i do to fix it?

Light came on about a month ago and my car feels like it pulses; when i drive it shifts funny and feels like it wants to die and when i come to a stop it runs the RPM's up and down between 1000 and 2000.